Polishing machine



March 2, 1948. G. H. MElNzER 2,437,034

I POLISHING MACHINE Filed sept. es,l 1944 2 sheets-sheet' 1 l E FIG-l Q L .f2

G. H. MElNzER /NVENTOR' Q www;

FIG 5 A TURA/Ey March 2, 1948. G. H. MElNzER 2,437,034

- POLISHING MACHINE 'l Filed Sept. 6, 1944 2 Sheets- SheetV 2 G H. MEINZER /NVENTOR TQM (4]. law.

A T TORNEV Patented Mar. 2, 1948 UNITED STATES Vi-"iiTENT lOFFICE 2,437,034 PoLIsHING MACHINE Gotthold Harry Meinzer, Glendale, Calif. Applicationseptember 6, 1944, Serial No. 553,126

This invention relates to portable apparatus for polishing, waxing, sanding or otherwise smoothing fixed solid surfaces such as iloors, pavements and automobile bOdies.

The portable polishing -devices currently in use are of two general types, in which the element bearing on the surface to be polished takes the form respectively of a disc rotating about its own center and of an endless belt.

These devices have several disadvantages which limit their utility. As in both forms the actual polishing element must move at a relatively low speed, a long reducing gear train is required, causing the device to be mechanically inefficient. This low efiiciency in turn requires the use of a relatively heavy motor, which reduces the portability of the machine and makes it cumbersome to handle. In neither of these forms is it practicable to construct a unit of Such weight as may be held in the hand, as for example for automobile polishing.

Again, both of these forms have a strong tendency to eject the polishing agent (wax or abrasive) from the immediate area being treated, the disc type by moving it outwardly from the center of the disc, the belt type by moving it ahead of the belt, which necessarily travels toward the unpolished part of the surface.

These structural disadvantages result, in either form, in a machine of excessive weight and consequent limited portability, a machine which is subject to rapid depreciation, which is too costly to be available for general household use, and which. cannot be constructed in such size and weight as to be applicable to other than horizontal plane surfaces.

The improvement over the above devices herein described lies basically in means for moving a non-rotating polishing element through a circular path of small radius, at high speed. This movement is produced by taking advantage of the inertia of a pair of relatively light weights afiixed to the motor shaft and revolving with it, thus avoiding the necessity for speed reduction or power transmission of any kind. The improvement is evidenced in the production of a machine of relatively light weight, having a ysharply reduced tendency to extrude the abrasive, of high efficiency and durability, and capable of being manufactured at a considerably reduced cost.

weight: thus in small size a resilient pad An illustrative embodiment of the invention is shownl in the attached drawings, in Awhich Fig. 1 is a vertical section through the machine, themotor and actuating weights being in elevation;

Fig. 2 is a plan view of the assembly;

Fig. 3 is an outline elevation of the assembly illustrating attachments which increase its utility for polishing extended horizontal surfaces such as floors;

2 Claims. (Cl. 51-170) Fig. 4 is a diagram of the assembly illustrating the forces which produce vibratory movement of the polishing element in its own plane;

Fig. 5 is a force diagram illustrating the proportioning of certain elements of the device.

Referring rst to Figs. y1 and 2, an electric motor lll is provided with a skirt II or other means by which it is rigidly supported from a platen I2 with its shaft perpendicular to the plane of the outer face of the platen. This element should be rigid and of comparatively light it may be formed of plywood, hardwood or a light metal, or in larger sizes of wood with metallic reinforcement.

To the lower (-outer) face of the platen is ailixed I3 which maybe of a carpet having a deep pile, of soft rubber or of sponge rubber. This soft pad is useful in oor waxing and polishing, a. renewable cloth I4 being folded over its surface and retained by suitable means such as the spring-contracted ring I5.

To the motor shaft I6 are attached eccentric weights I1 and I8, these weights revolving with the armature ofthe motor and being at least substantially in phase. lThe Irelations of these unbalanced weights to the system as a whole will be described.

At opposite sides of the motor, brackets I9 and 2G, attached to the motor lor the skirt as may be convenient, carry resilient elements 2I-2I to which the handle or guiding element is attached. These elements isolate the vibration of the system, prevent its transmission to the hand of the operator and avoid damping the vibration of the system by any laterally applied force used in moving the device over the work surface. They must be fully resilient: thick-walled, soft rubber tubes or closed coil, strings are suitable for use in this position, the drawing illustrating rubber tubes maintained in tension between the brackets.

A convenient guiding element for small units, such as are suitable for polishing automobile bodies and other curved or vertical surfaces, is shown in Fig. 2. A yoke 22-22 projected from a hand grip 23 is attached to resilient elements 2I at approximate midpoint, as indicated at 2li- 24. The brackets I9 and 20 should be so placed that this midpoint lies approximately in a plane passing throughy the center of mass of the system (plane CP of Fig. 4) to avoid tilting of the system by any laterally applied force.

A flexible double electricalconductor 25 passes through the hand grip and is provided with a thumb switch 26. The connections from the switch to the motor may be as convenient and v and provided with a. counterweight by which.`

the weight of the unit is balanced. The rst named arrangement is adapted to units" o'fi. the! smallest size; the latter to large units.

In assemblies of larger size, such asar'e adapt'- ed to polishing and sanding floors and-pave;-

ments, it may be desirable to modify the guiding element in the manner illustrated in Fig; 3; In'

this modification the yoke member 22 is attached to an arm 28 which is projected downwardly as y at 29 and terminates in a foot piece 30, which may be covered with felt for use on floors or faced with metal or hardwood for use in sanding. A handle 3l is pivoted on` the angle memberV as at 32. This arrangement prevents the operator from bearing down on the vibrating assembly and avoids danger of tilting.

The essential elements of the above structure and the manner in which it functions are illus# trated in the diagram Fig. 4 in which only the outlines of the primary elements are shown.

The motor lil is so mounted that the axis X of shaft I6 is normal to plane P of platen- I2 and passes at least approximately through the center of the platen. The eccentric weights I7 and I8 have offsets F1 and F2. The center of mass of the system is indicated atV C and the plane parallel to plane P and passing throughthe center of mass is indicated at CP.

In operation, as the motor shaft rotates above the critical speed of the system, the two unbalanced weights generate a vibration aboutV the axis X passing through the center of mass. For efficient polishing, the surface P should vibrate in its own plane. To produce this result, the

. rotating vectors F1 and F2 must be at least substantially and should be exactly in phase and must have equal moments about the center of gravity C of the vibrating system. Mathematically expressed, vector Fi multiplied by arm Ai must equal vector F2 multiplied by arm-A2 When this condition obtains (abovethe critical speed) we have a freely vibrating system with a circular path of vibration about anaxis pass'- ing through the center of mass and in planes parallel to the plane of the platen and normal to the axis of rotation.

The amplitude of vibration bearsno relation to the rotative speed of the motor, the radius of the orbit being proportional to the ratio of the sum of the rotating vectors F1 an'dFz. to the total mass of the vibrating system. Thus,` in the force diagram Fig. 5, whichillustrat'es actual values for a working hand polisher, vector Fi=506 centimeter grams, vector F2'=101`2 cm. gr. and the resultant force F3 eifective'at the center of mass is 1518 cm. gr. The arm Ai. is 10.2 cm. and the arm A2 is'5.1 cm. As

the force F3 is applied in a plane normal to axis X. The actual weight of the vibrating system is 3855 gr. and the radius of orbit is the ratio 1518 to 3855 or 0.4 cm. approximately. This unit is provided with a volt A. C. motor rating l/is'H P. and rotating 1800 R. P. M., and the diameter of platen l2 is aboutseven inches.

`As all parts of the polishing surface carry the same weight and move at the same speed they 'are' equally effective, a sharp contrast to the disc polishers in which only the outer portions of the discrnove'fast enough to be useful. Polishing withthe describedM device is effected by rapid movement under light pressure, is very rapid, and there" isv little or no tendency to squeeze out the polishing or abrasive agent.

Because of the high vibratory speed and the lightr bearing on the surface to be treated, frictional resistance is reduced to the point at which it does not damp vibration and in any ordinary service need not be taken into account in calculating the radius of orbit or the relative values of F XA. For the same reason there is substantially no resistance to movement of the device over horizontal surfaces, and. the machine while in operation may be guided in-all directions vwithout appreciablel effort.

I claim as my invention:

1. A device adapted to smoothing solid surfaces, comprising-z a platen; a-motorv rigidlymounted on` said platen with: its shaft perpendicular thereto; a` pair of. eccentricv weights attached to saidshaft, rotating therewith and positioned on opposite sides of the center of mass of the system, said-weights beingY at least substantially in phase andf being so proportioned and positioned as to produce vibration of the system in planes parallel tothe plane Vof said platen; a handle, and resilient means'for attaching said'handle to said motor on opposite sidesthereo'f;

2; A device adapted to smoothing solid surfaces, comprising: av platen;` af motor rigidly mounted on saidv platen with its shaftA perpendicular thereto; a pair of eccentricweights attached. t0 said shaft, rotating therewith andV positioned on opposite'si'desof the center of mass of the system, said-weightsfbeing at leastfsubstantiallyfin phase andl being so proportioned.` and,f positioned' as t0 produce vibration of the system inlplan'es parallel to -:the planeof said platen; a handle, .and resilient means for attaching said handle to said motor on opposite sides thereof, said attachment being madeV in a pla-ne passing substantially` through said cen-terv of mass.'y

GOTTHOLD-HARRY MEINZER.

alsiiiiltEncresY CITED Thevfollowin'g referencesare of record in the file of this patent:

UNITED STATES PATENTS 

